3D semiconductor integrated circuit device and method of manufacturing the same

ABSTRACT

A 3D semiconductor integrated circuit device and a method of manufacturing the same are provided. An active pillar is formed on a semiconductor substrate, and an interlayer insulating layer is formed so that the active pillar is buried in the interlayer insulating layer. The interlayer insulating layer is etched to form a hole so that the active pillar and a peripheral region of the active pillar are exposed. An etching process is performed on the peripheral region of the active pillar exposed through the hole by a certain depth, and a space having the depth is provided between the active pillar and the interlayer insulating layer. A silicon material layer is formed to be buried in the space having the depth, and an ohmic contact layer is formed on the silicon material layer and the active pillar.

CROSS-REFERENCES TO RELATED APPLICATION

This application claims priority under 35 U.S.C. 119(a) to Korean application No. 10-2014-0102518, filed on Aug. 8, 2014, in the Korean intellectual property Office, which is incorporated by reference in its entirety as set forth in full.

BACKGROUND

1. Technical Field

Embodiments relate to a three dimensional (3D) semiconductor integrated circuit device and a method of manufacturing the same, and more particularly, to a semiconductor integrated circuit device having a wrap-around contact structure and a method of manufacturing the same.

2. Related Art

Memory devices are generally provided as internal semiconductor integrated circuit devices of computers or other electronic apparatuses. Typical examples of memory devices include random access memories (RAMs), read only memories (ROMs), dynamic RAMs (DRAMs), synchronous DRAM (SDRAM), flash memories, and variable resistive memory devices. Variable resistive memory devices include programmable conductive memory devices, resistive RAMs (ReRAMs), and phase-change RAMs (PCRAMs).

Nonvolatile memory devices may be used in broad electronic applications to provide high integration density, high reliability, and low power consumption.

Variable resistive memory devices may include a plurality of memory cells arranged in matrix form. The memory cells may include an access device such as a diode, a field effect transistor (FET), or a bipolar junction transistor (BJT). The access device may be coupled to a word line extending along a row of an array. Memory elements in the memory cells may be coupled to a bit line extending along a column of the array. In this manner, the access device of the memory cell may select a word line coupled to a gate and the memory cell may be accessed through a row decoder which activates the rows of the memory cell.

Currently, a transistor having a 3D vertical channel structure is used as the access device of the memory cells to increase integration density. As is well-known, a transistor having the 3D vertical channel structure may include a pillar-shaped active region, a gate formed on an outer circumference of the active region, a drain formed in an upper portion of the active region, and a source formed in a lower portion of the active region or formed in a semiconductor substrate which is in contact with the lower portion of the active region. A heating electrode, a variable resistance layer, and a bit line are sequentially formed to be electrically coupled to the drain of the transistor, and thus the resistive memory cell is completed.

To obtain ohmic contact between the drain and the heating electrode, a silicide layer is formed between the drain and the heating electrode. Currently, endeavors for improving the operation current in the variable resistive memory device continue, and thus, technology for improving contact properties between the drain and the silicide layer or between a lower electrode and the silicide layer has been suggested.

SUMMARY

According to an embodiment, there is provided a method of manufacturing a semiconductor integrated circuit device. An active pillar is formed on a semiconductor substrate, and an interlayer insulating layer is formed so that the active pillar is buried in the interlayer insulating layer. The interlayer insulating layer is etched to form a hole so that the active pillar and a peripheral region of the active pillar are exposed. An etching process is performed on the peripheral region of the active pillar exposed by the hole to certain depth, and a space having the depth is provided between the active pillar and the interlayer insulating layer. A silicon material layer is formed to be buried in the space having the depth, and an ohmic contact layer is formed on the silicon material layer and the active pillar.

According to an embodiment, there is provided a method of manufacturing a semiconductor integrated circuit device. Active pillars, each of which include a gate insulating layer and a gate electrode, are surrounded on an outer circumference, are prepared on a semiconductor substrate, and an interlayer insulating layer is formed to be buried between the active pillars. The interlayer insulating layer is etched to form a hole so that a top of the active pillar and the gate insulating layer are exposed. The exposed gate insulating layer is etched by a certain depth to form a space between the interlayer insulating layer and the active pillar, and a silicon material is formed in the space. An ohmic contact layer is formed on the silicon material and the active pillar, and a lower electrode and a variable resistance material layer are sequentially formed on the ohmic contact layer.

According to an embodiment, there is provided a semiconductor integrated circuit device. The semiconductor integrated circuit device may include an active pillar of which a gate electrode is covered on an outer circumference, a drain region is formed in a portion over the gate electrode, and a source region is formed in a portion below the gate electrode, a gate insulating layer located between the active pillar and the gate electrode, a contact extension region located on an outer circumference of the drain region in the active pillar and the gate insulating layer, and an ohmic contact layer formed on the contact extension region.

The contact extension region may be formed on the outer circumference of the active pillar in a cylinder form. Alternatively, the contact extension region may be formed in a cap form to cover the outer circumference of the active pillar and a top of the active pillar.

These and other features, aspects, and embodiments are described below in the section entitled “DETAILED DESCRIPTION”.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGS. 1 to 8 are cross-sectional views illustrating a method of manufacturing a semiconductor integrated circuit device according to an embodiment;

FIGS. 9 to 12 are cross-sectional views illustrating a method of manufacturing a semiconductor integrated circuit device according to an embodiment; and

FIG. 13 is an enlarged cross-sectional view of a contact portion between a selective epitaxial growth (SEG) layer and a silicide layer of FIG. 12.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments will be described in greater detail with reference to the accompanying drawings. Exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of the exemplary embodiments (and intermediate structures). Modifications in the shape of the illustrations are possible due to differences in manufacturing techniques and/or tolerances. Thus, exemplary embodiments should not be construed as limited to the particular shapes of regions illustrated. In the drawings, lengths and sizes of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. It is also understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present.

It is not intended that the embodiments be limited to the drawings. Although a few embodiments will be shown and described, it will be appreciated that changes may be made to these exemplary embodiments with the resultant still falling within the spirit and scope of the invention.

Referring to FIG. 1, a pillar 110 a may be formed in a predetermined region of a semiconductor substrate 100 through a general method. The pillar 110 a may be formed by etching the semiconductor substrate 100. Alternatively, the pillar 110 a may be formed by depositing a semiconductor layer (not shown) on the semiconductor substrate 100 and etching a predetermined portion of the semiconductor layer. The pillar 110 a may correspond to an active region of a transistor. After the pillar 110 a is formed, a channel and drain may be formed in the pillar 110 a. A gate insulating layer 115 is formed on a sidewall of the pillar 110 a and on a surface of the semiconductor substrate 100 between pillars 110 a. The gate insulating layer 115 may be formed by oxidizing a surface of the semiconductor substrate 100 in which the pillar 110 a is formed. A conductive material layer (not shown) may be formed on the semiconductor substrate 100 in which the gate insulating layer 115 is formed, and then anisotropically etched. Thus, a surrounding gate 120 may be formed on the sidewall of the pillar 110 a. The surrounding gate 120 may be formed at a level lower than that of the pillar 110 a. The surrounding gate 120 is etched to be isolated from neighboring surrounding gate 120. First high concentration impurities may be implanted into a lower portion of the isolation region to form a preliminary source region 125. In the process of forming the surrounding gate 120, the gate insulating layer 115 located on the top of the pillar 110 a may be removed as shown in FIG. 1. Second high concentration impurities 130 may be implanted in an exposed upper portion of the pillar 110 a for forming a junction region. An interlayer insulating layer 135 may be formed to insulate the pillars 110 a. The interlayer insulating layer 135 may extend to a level higher than that of an upper surface of the pillar 110 a so that the pillars 110 a may be sufficiently buried in the interlayer insulting layer 135 and a lower electrode region or a variable resistance region be defined over each of the pillars 110 a. The interlayer insulating layer 135 may be, for example, a silicon nitride layer.

Referring to FIG. 2, the interlayer insulating layer 135 is etched to form a hole H so that an upper surface of the pillar 110 a and an upper sidewall of the pillar 110 a are exposed by the hole H. For example, the hole H may be formed to expose the gate insulating layer 115 formed on the outer circumference of the pillar 110 a. Thus, a width a2 of the hole H may be set larger than a sum of a width a1 of the pillar 110 a and a thickness (or a width) of the gate insulating layer 115. Then, the gate insulating layer 115 exposed through the hole H is etched by a certain thickness to form a space between the pillar 110 a and the interlayer insulating layer 135 so that an upper sidewall of the pillar 110 a is exposed.

Referring to FIG. 3, a silicon material 140 may sufficiently fill in the hole H and the space which is created by removing the gate insulating layer 115 between the interlayer insulating layer 135 and the pillar 110 a. The silicon material 140 may be an undoped polysilicon layer, and may be formed through a low temperature chemical vapor deposition (CVD) method to easily fill in the space.

Referring to FIG. 4, a chemical mechanical polishing (CMP) process may be performed on the silicon material 140 so that the interlayer insulating layer 135 is exposed. Then, the silicon material 140 may be further etched back to be left in a bottom portion of the hole H. The silicon material 140 may be provided on an upper portion of the pillar 110 a and extend between the interlayer insulating layer 135 and the pillar 110 a to fill in the space. Under this structure, the silicon material 140 may be in a cap shape, as shown in FIG. 4. In another embodiment, the silicon material 140 may be etched back until the pillar 110 a is exposed. Under this structure, the silicon material 140 may fill in the space between the interlayer insulating layer 135 and the pillar 110 a and may be in a cylinder shape, as shown in FIG. 5. In FIGS. 4 and 5, the reference numerals 140 a and 140 b denote etched-back silicon materials. In the etch back process of the silicon material 140, a surface of the interlayer insulating layer 135 may be also etched back by a certain thickness. Then, an impurity may be implanted into the silicon material 140 a or 140 b so that the silicon material 140 a or 140 b may have substantially the same concentration as the upper portion of the pillar 110 a. The silicon material 140 a or 140 b is located on an upper surface of or an outer circumference of the pillar 110 a and serves as a contact extension region.

Referring to FIG. 6, a metal layer 145 may be deposited on a upper surface of the silicon material 140 a or 140 b and the pillar 110 a to fill in the hole H. For example, the metal layer 145 may include a stacked layer of a titanium layer and a titanium nitride layer. FIG. 6 illustrates the metal layer 145 formed on the semiconductor substrate in which the silicon material 140 a is formed, as illustrated in FIG. 4. However, in another embodiment, the metal layer 145 may be formed on the semiconductor substrate in which the silicon material 140 b is formed, as shown in FIG. 5.

Referring to FIG. 7, a heat treatment process may be performed so that the metal layer 145 and the silicon material 140 a (or the metal layer 145, the pillar 110 a, and the silicon material 140 b) react with each other. Thus, the surface of the silicon material 140 a or 140 b and the surface of the pillar 110 a, which is in contact with the metal layer 145, reacts with the metal layer 145 to form a silicide layer 150, which serves as an ohmic contact layer, on the pillar 110 a and the silicon material 140 a or 140 b. The silicide layer 150 may have substantially the same width as the width a2 of the hole H. By controlling the heat treatment process, the silicide layer 150 may extend along a lateral surface of the pillar 110 a, and thus a contact area of the silicide layer 150 with the pillar 110 a may further extend. Further, by controlling the heat treatment reaction, the silicon material 140 a or 140 b may be entirely or partially changed into the silicide layer. Then, the non-reacted metal layer 145 may be removed through a general method. Thus, a silicide area of the silicide layer, which is in contact with a lower electrode and drain region to be formed later, may be substantially increased, and the contact areas of the silicide layer with the lower electrode and the drain region may be increased.

In the heat treatment process of the silicon material 140 a or 140 b, the impurity implanted in the upper portion of the pillar 110 a and the impurity implanted in the preliminary source region 125 below the pillar 110 a may be activated, and a common source region S may be formed below the pillar 110 a and a drain region D may be formed in the upper portion of the pillar 110 a.

Referring to FIG. 8, a lower electrode 155 is formed in the hole H through a general method to be in contact with the silicide layer 150, and a variable resistance material layer 160 is formed on the lower electrode 155. In another embodiment, the lower electrode 155 and the variable resistance material layer 160 may be buried within the hole H. The variable resistance material layer 160 may include various materials such as a PCMO (Pr_(1-x)Ca_(x)MnO₃) layer for a ReRAM, a chalcogenide layer for a PCRAM, a magnetic layer for a MRAM, a magnetization reversal device layer for a spin-transfer torque magnetoresistive RAM (STTMRAM), or a polymer layer for a polymer RAM (PoRAM).

According to the embodiment, since an area of the silicide layer 150 serving as an ohmic contact layer extends through the contact extension region which is provided on the outer circumference of the pillar, a contact area between the lower electrode 155 and the silicide layer 150 and a contact area between the silicide layer 150 and the drain D may increase, and contact resistance may reduce. Thus, a turn-on current characteristic of a switching device of a variable resistive memory apparatus may improve.

In another embodiment, the silicon material 140 may be replaced with a selective epitaxial growth (SEG) layer 142, as shown in FIG. 9. Specifically, after the hole H exposing the top and upper sidewall of the pillar 110 a is formed, the selective epitaxial growth (SEG) layer 142 may be grown. As is known, the SEG layer 142 has a single crystalline structure and may be grown using a silicon material as a seed. In an embodiment, the SEG layer 142 is grown to a certain thickness using the exposed top and upper sidewall of the pillar 110 a as a seed. The SEG layer 142 may extend between the pillar 110 a and the interlayer insulating layer 135 to a thickness 10 to 20% larger than or smaller than a target thickness of the silicide layer, which will be formed later. The SEG layer 142 may include a doped SEG layer. That is, the growth process and the impurity implantation process may be simultaneously performed by forming the SEG layer 142 containing impurities. When the doped SEG layer 142 is formed through the above-described process, the SEG layer 142 may have an impurity concentration profile in which an impurity concentration gradually reduces when going down from a top of the SEG layer 142 toward the semiconductor substrate 100. Therefore, the silicide layer may be easily formed and a junction region may be easily defined in a subsequent process. The embodiments are not limited to by this method of forming the doped SEG layer. In another embodiment, for example, the doped SEG layer may be formed by forming an undoped SEG layer and implanting an impurity through a separate impurity implantation process.

Referring to FIG. 10, a metal layer 145 is formed on the SEG layer 142.

Referring to FIG. 11, the metal layer 145 reacts with the SEG layer 142 through a heat treatment process to form a silicide layer 150. Since a width a2 of the SEG layer 142 is substantially larger than the width a1 of the pillar 110 a, the width of the silicide layer 150 formed on the SEG layer 142 may be the width a2 of the SEG layer 142, which is larger than the width a1 of the pillar 110 a. Therefore, a contact area between a lower electrode, which will be formed later, and the silicide layer 150 increases. In the heat treatment process of forming the silicide layer 150, the impurity implanted in the upper portion of the pillar 110 a and the impurity implanted below the pillar 110 a may be activated. A non-reacted metal layer 145 may be removed. A heating electrode 155 and a variable resistive pattern 160 may be sequentially formed on the silicide layer 150. As a result, a common source region S may be formed below the pillar 110 a and a drain region D may be formed in the upper portion of the pillar 110 a.

Referring to FIG. 12, after the SEG layer 142 is formed as shown in FIG. 11, a heat treatment process may be further performed against a surface of the SEG layer 142 in an atmosphere of hydrogen (H₂). When the heat treatment process is performed in the atmosphere of hydrogen (H₂), impurities in the inside of the SEG layer 142 may be activated and then move upward to the surface of the SEG layer 142. Thus, an SEG layer 142 a ends up with a waved surface topology. Due to the waved surface of the SEG layer 142 a, the surface area of the SEG layer 142 a significantly increases. In lieu of the hydrogen heat treatment process, any process capable of causing a waved surface topology may be employed.

Referring to FIG. 13, a metal layer is deposited on the SEG layer 142 a having the waved surface topology and subject to heat treatment to form a silicide layer 150 as described above. Therefore, the contact area between the SEG layer 142 a and the silicide layer 150 may increase due to the waved surface topology of the SEG layer 142 a, and thus the contact resistance between the SEG layer 142 a and the silicide layer 150 may decrease. In an embodiment, the topology of the SEG layer 142 a is transferred to the silicide layer 150, and thus the silicide layer 150 may also have a waved surface topology. Therefore, a contact area between the silicide layer 150 and a lower electrode, which is formed later, may increase.

The above embodiments are illustrative and not limitative. Various modifications are possible. Embodiments are not limited to any specific type of semiconductor device. 

What is claimed is:
 1. A method of manufacturing a semiconductor integrated circuit device, the method comprising: forming an active pillar in a semiconductor substrate; forming a gate electrode to surround sidewall of the active pillar; forming an interlayer insulating layer over the semiconductor substrate and the active pillar; forming a hole by etching the interlayer insulating layer so that an upper surface of the active pillar is exposed by the hole; forming a space extending from the hole down to between an upper sidewall of the active pillar and the interlayer insulating layer so that the upper sidewall of the active pillar is exposed and an upper surface of the gate electrode is not exposed; forming a silicon material layer in the space; and forming an ohmic contact layer on the silicon material layer and on the active pillar in the hole.
 2. The method of claim 1, wherein the forming of the silicon material layer includes: forming a polysilicon layer which fills in the space and extends over the upper surface of the active pillar.
 3. The method of claim 2, wherein forming the polysilicon layer includes: performing chemical mechanical polishing against the polysilicon layer to expose an upper surface of the interlayer insulating layer, wherein the upper surface of the interlayer insulating layer is located at a level higher than the upper surface of the active pillar; and additionally etching back the polysilicon layer so that an upper surface of the polysilicon layer is located at a level between the upper surface of the interlayer insulating layer and the upper surface of the active pillar.
 4. The method of claim 2, wherein the polysilicon layer includes an undoped polysilicon layer.
 5. The method of claim 2, wherein the polysilicon layer is formed through a low temperature chemical vapor deposition (CVD) method.
 6. The method of claim 1, further comprising: between the forming of the silicon material layer and the forming of the ohmic contact layer, implanting an impurity into the silicon material layer.
 7. The method of claim 1, wherein the forming of the silicon material layer includes growing a selective epitaxial growth (SEG) layer so that the SEG layer extends into the space and the hole using the upper surface and the upper sidewall surface of the active pillar as a seed.
 8. The method of claim 7, wherein the SEG layer includes an impurity.
 9. The method of claim 7, further comprising: after the growing of the SEG layer, performing a surface treatment process against the SEG layer to form a waved surface.
 10. The method of claim 9, wherein the surface treatment process against the SEG layer includes a hydrogen heat treatment process.
 11. The method of claim 1, further comprising: between the forming of the active pillar and the forming of the interlayer insulating layer, forming a gate insulating layer surrounding a lower sidewall of the active pillar; forming the gate electrode over the gate insulating layer; implanting an impurity into the semiconductor substrate between the active pillar and a neighboring active pillar for isolating the active pillars and the neighboring active pillar from each other; and implanting an impurity into an upper portion of the active pillar, wherein the gate electrode is spaced from the silicon material layer formed in the space.
 12. The method of claim 11, wherein the forming of the ohmic contact layer includes: forming a metal layer over the silicon material layer; performing a heat treatment process against the metal layer to form a silicide layer at an interface between the silicon material layer and the metal layer; and removing the metal layer, wherein, by the heat treatment process, the impurities implanted into the semiconductor substrate between the active pillar and the neighboring active pillar are activated to form a source region, and wherein, by the heat treatment process, the impurities implanted into the upper portion of the active pillar are activated to form a drain region.
 13. The method of claim 11, wherein the forming the hole, the interlayer insulating layer is etched to expose the upper portion the active pillar and the gate insulating layer.
 14. The method of claim 1, further comprising: forming a lower electrode in the hole to contact ohmic contact layer; and forming a variable resistance material layer over the lower electrode.
 15. A method of manufacturing a semiconductor integrated circuit device, the method comprising: providing active pillars in a semiconductor substrate; providing a stack of a gate insulating layer and a gate electrode over a lower sidewall of each of the active pillars; providing an interlayer insulating layer extending over the active pillars to fill with a first space between the active pillars; forming a hole by etching the interlayer insulating layer so that the hole exposes an upper surface of each of the active pillars and the gate insulating layer; etching the exposed gate insulating layer by a given depth to form a second space extending from the hole to between the interlayer insulating layer and an upper sidewall of each of the active pillars, wherein the gate electrode is not exposed by the second space; forming a silicon material layer in the second space; forming an ohmic contact layer on the silicon material layer and on the active pillars in the hole; and sequentially forming a lower electrode and a variable resistance material layer over the ohmic contact layer, wherein the lower electrode is formed in the hole.
 16. The method of claim 15, wherein the forming of the silicon material layer includes: forming a polysilicon layer which fills in the second space and extends over the upper surface of each of the active pillars; performing chemical mechanical polishing against the polysilicon layer to expose an upper surface of the interlayer insulating layer; and etching back the polysilicon so that an upper surface of the polysilicon layer is located at a level between the upper surface of the interlayer insulating layer and the upper surface of each of the active pillars.
 17. The method of claim 16, wherein the polysilicon layer includes an undoped polysilicon layer, and wherein the polysilicon layer is formed by a low temperature chemical vapor deposition (CVD) method.
 18. The method of claim 17, further comprising, between the forming of the silicon material layer and the forming of the ohmic contact layer, implanting an impurity into the silicon material layer.
 19. The method of claim 15, wherein the forming of the silicon material layer includes: growing a selective epitaxial growth (SEG) layer so that the SEG layer extends into the space and the hole using the upper surface and the upper sidewalls of the active pillars as a seed.
 20. The method of claim 19, wherein the SEG layer includes an impurity.
 21. The method of claim 19, further comprising: after the growing of the SEG layer, performing a surface treatment process against the SEG layer to form a waved surface.
 22. The method of claim 21, wherein the surface treatment process of the SEG layer includes a hydrogen heat treatment process.
 23. The method of claim 15, further comprising: between the forming of the active pillars and the forming of the interlayer insulating layer, implanting an impurity into the semiconductor substrate between the active pillars; and implanting impurities into an upper portion of the active pillars.
 24. The method of claim 15, wherein the forming of the ohmic contact layer includes: forming a metal layer over the silicon material layer; performing a heat treatment process against the metal layer to form a silicide layer; and removing the metal layer, wherein, by the heat treatment process, the impurities implanted into the semiconductor substrate between active pillars are activated to form a source region, and wherein, by the heat treatment process, the impurities implanted into the upper portion of the active pillars are activated to form a drain region. 